1. Field of the Invention
This invention relates to a thin film multi-junction photovoltaic array module of solar electric power systems.
2. The Prior Art
U.S. Pat. No. 5,505,789 to Fraas et al discloses a line-focus photovoltaic module using solid optical secondaries for improved radiation resistance. This invention consists of an array of linear arched fresnel lenses with a linear photovoltaic cell receiver located along the focal line of each lens. The optical secondaries may be parabolic in shape.
These systems disclose the combination of fresnel lenses, and parabolic reflectors. U.S. patent application Ser. No. 09/687,960, now U.S. Pat. No. 6,384,320 discloses a combination of a fresnel lens, compound parabolic reflector incorporated with third optical concentration glass lenses and multi-junction solar cells for photovoltaic electric energy conversion.
The invention relates to a thin film multi-junction photovoltaic array module of solar electric power generation systems. The high performance photovoltaic (PV) array module with multi-junction concentrator solar cells converts directly 30 or 40% of received solar energy to electricity.
A photovoltaic solar cell is a semiconductor device that converts sunlight directly to electricity through the Photovoltaic Effect. One of the important developments of PV applications is the lowering of the system cost through the design of the PV array module to more efficiently convert the sunlight directly to electricity.
The PV array module contains multi-step concentrations of sunlight with Fresnel lenses, CPC reflectors and specially shaped glass lenses that can be made with much smaller surface areas of expensive multi-junction concentrator solar cells in the system. Solar high-concentration and high-efficiency multi-junction solar cells are the essential factors for lowering the cost of PV array modules which produce electricity.
To meet the requirement of ultra high efficiency, concentrator solar cells, such as tandem GalnP/GalnAs and other multi-junction concentrator solar cells such as at least three-junction solar cells, are provided to generate more than 32 or 45%.